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Key Discovery Strengthens Linkage Between Pesticide Use and Colony Collapse Disorder

Scientists around the world have been trying to identify the risk factors driving honeybee Colony Collapse Disorder (CCD). There is near-universal agreement that the problem remains severe; many factors can trigger CCD, and of these, several appear to depend on a weakened bee immune system; and, exposure to pesticides, and in particular the persistent, systemic nicotinyl insecticides are likely to be involved in many CCD episodes.

In an important breakthrough, scientists in Europe have discovered a major new, widespread exposure pathway through which bees are ingesting nicotinyl insecticides in virtually all intensively farmed regions – honeybee sources of drinking water. In October, 2009 at a scientific meeting in Paris, Hedwig Riebe summarized recent research on this new exposure pathway (Riebe, 2009).

In the morning and throughout the growing season, essentially all plants emit water in the form of guttation drops. Guttation drops come from inside plant cells, and can carry with them, into the outside world, natural or man-made chemicals that are present in plant cells, such as residues of systemic pesticides that have moved, as they are designed to do, throughout plant tissues. The latest results from European research found 20 parts per billion of nicotinyl insecticides in guttation droplets, almost certainly enough to deliver a dangerous dose to nearby bees.

Inside hives during warm spring and summer nights, bees are hard at work fanning the hive with their wings to help keep the queen comfortable and the brood safe. Each morning at first flight, the bees are dehydrated and thirsty, and seek out a nearby source of moisture. The drops on leaves in nearby fields, typically a mixture of moisture from guttation and dew, are a favorite first stop and common source of hydration. If the field was planted to a seed treated with a nicotinyl insecticide, or if the field/crop has been sprayed with a nicotinyl, the bees will be exposed to some level of systemic nicotinyl insecticide.

In some cases this exposure will prove deadly, as documented in 2009 European research. In other sub-acute exposure cases, the bees ingest enough nicotinyl to weaken their immune system, or disrupt their sense of direction and ability to navigate, or both. These sub-acute impacts are widely recognized factors contributing to or occurring during CCD.

Source: “Exposition Paths of Neonicotinoids,” Dr. Hedwig Riebe, DBID, Paris, France, October 12, 2009. Posted at – http://www.organic-center.org/science.pest.php?action=view&report_id=161

Courtesy of The Scoop; http://www.organic-center.org/

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